The present invention pertains to axial flow type combines in which the threshing and separating mechanism extends substantially longitudinally in the combine to the direction of travel and, essentially, comprises a rotor rotatably mounted in a casing having a threshing concave disposed in the lower portion thereof, and a separation grate rearward of said concave. In operation, crop material is fed to the forward or inlet end of the concave and rotor to a space therebetween which comprises a threshing region. In this region, the crop material is conveyed spirally as it moves axially rearwardly therethrough to effect separation of the grain from the crop material and deliver the waste material usually to the rearward end of the combine for discharge therefrom onto the field.
In normal practice, there is a relatively small clearance between the rotor and the casing which causes difficulties incident to introducing the material into the casing. Accordingly, one effective solution for increasing the feeding capacity employs auger means on the forward end of the rotor to aggressively transfer crop material from the crop elevator of the combine to the inlet end of the threshing and separating mechanism for treatment of the same within the threshing region.
Various other problems have been encountered in the past during efforts to provide efficient crop handling units for use in all types of crop material and in varying field and climatic conditions. For example, variable spacing between the rotor and concave has been contemplated for the purpose of alleviating plugging at the inlet end of the threshing region of axial flow type combines. Devices of this nature are shown in U.S. Pat. No. 3,631,862 issued to E. W. Rowland-Hill et al on Jan. 4, 1972, and U.S. Pat. No. 3,949,761 issued to F. H. Mortier et al on Apr. 13, 1976. These patents show unique structure directed to mechanisms for adjusting the position of a concave in an axial flow type combine to improve crop handling in the threshing region.
It is generally recognized that an important aspect of the operation of any combine harvester is the need for optimum threshing and separating characteristics along with a minimum amount of required adjustments regardless of the type of crop being handled. To this end, the effectiveness of an axial flow type combine can be improved if spacing between the concave and rasp bars is changed to accommodate varying types of crop having different characteristics, e.g., grain size. The structure shown in the patents mentioned above, although not addressed to the specific problem of accommodating various type crops, can be utilized to accomplish that end.
From the foregoing, and to summarize, it will be seen that previous attempts to alleviate plugging problems have resulted in the development of certain structures such as that shown in the mentioned patents. However, the present invention provides variable spacing means which are different from the means in the aforementioned patents for reasons set forth hereinafter and details thereof are as follows.